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Young star clusters immersed in intermediate-age fields in the Small Magellanic Cloud We present CCD photometry in the Washington C and T1 filtersfor six star clusters (B34, NGC256, NGC265, NGC294, IC1611 and NGC376)in the Small Magellanic Cloud (SMC) and their surrounding fields. Theresultant colour-magnitude diagrams (CMDs) extend from T1 ~14 to as faint as T1 ~ 22 revealing the main-sequenceturnoffs of the clusters. Adopting a metallicity of Z = 0.004, wecompare our cluster photometry with theoretical isochrones in theWashington system in order to derive ages. To facilitate agedetermination of the surrounding fields, we use the magnitude differencebetween the helium-burning red clump stars and the main-sequenceturnoff. Finally, we estimate mean metallicities for the field stars bycomparing the location of the field red giant branch with standard giantbranches for Galactic globular clusters of known abundance, correctedfor age effects. Combining these results with our previous work, we finda clear trend of younger clusters being located closer to the centre ofthe SMC. In addition, there is a tendency for the mean metallicity andits dispersion to be greater inside 4° of the SMC's centre ascompared to outside this radius. As far as the properties of the fieldstars are concerned, we find little correlation between the ages of theclusters and those of the field stars against which they are projected.Clearly, more work needs to be done to clarify these trends.
| Three clusters of the SMC from ACS/WFC HST archive data: NGC 265, K 29 and NGC 290 and their field population Aims.We determine the age, metallicity and initial mass function ofthree clusters, namely NGC 265, K29, NGC 290, located in the main body ofthe Small Magellanic Cloud. In addition, we derive the history of starformation in the companion fields. Methods: We make use of ACS/WFC HSTarchive data. For the clusters, the age and metallicity are derivedfitting the integrated luminosity function with single synthetic stellarpopulation by means of the χ2 minimization. For thecompanion fields, the history of star formation is derived using theχ2 minimization together with the downhill-simplexmethod. Results: For the clusters we find the following ages andmetallicities: NGC 265 has log(Age)=8.5±0.3 yrand metallicity 0.004±0.003 (or [ Fe/H]=-0.62); K29 has log(Age)=8.2±0.2 yr and metallicityZ=0.003±0.002 (or [ Fe/H]=-0.75); NGC 290 haslog(Age)=7.8±0.5 yr and metallicity 0.003±0.002 (or [Fe/H]=-0.75). The superior quality of the data allows the study of theinitial mass function down to M ˜ 0.7 Mȯ. Theinitial mass function turns out to be in agreement with the standardKroupa model. The comparison of the NGC 265luminosity function with the theoretical ones from stellar models bothtaking overshoot from the convective core into account and neglectingit, seems to suggest that a certain amount of convective overshoot isrequired. However, this conclusion is not a strong one because thiscluster has a certain amount of mass segregation which makes itdifficult to choose a suitable area for this comparison. The starformation rate of the field population presents periods of enhancementsat 300-400 Myr, 3-4 Gyr and finally 6 Gyr. However it is relativelyquiescent at ages older than 6 Gyr. This result suggests that at olderages, the tidal interaction between the Magellanic Clouds and the MilkyWay was not able to trigger significant star formation events.
| Integrated-light VRI imaging photometry of globular clusters in the Magellanic Clouds We present accurate integrated-light photometry in Johnson/Cousins V, Rand I for a sample of 28 globular clusters in the Magellanic Clouds. Themajority of the clusters in our sample have reliable age and metallicityestimates available in the literature. The sample encompasses agesbetween 50 Myr and 7 Gyr, and metallicities ([Fe/H]) between -1.5 and0.0 dex. The sample is dominated by clusters of ages between roughly 0.5and 2 Gyr, an age range during which the bolometric luminosity of simplestellar populations is dominated by evolved red giant branch stars andthermally pulsing asymptotic giant branch (TP-AGB) stars whosetheoretical colours are rather uncertain. The VRI colours presented inthis paper have been used to calibrate stellar population synthesismodel predictions.
| Age distribution of young clusters and field stars in the Small Magellanic Cloud Aims.In this paper we discuss the cluster and field star formation inthe central part of the Small Magellanic Cloud. The main goal is tostudy the correlation between young objects and their interstellarenvironment. Methods: . The ages of about 164 associations and 311clusters younger than 1 Gyr are determined using isochrone fitting. Thespatial distribution of the clusters is compared with the HI maps, withthe HI velocity dispersion field, with the location of the CO clouds andwith the distribution of young field stars. Results: .The clusterage distribution supports the idea that clusters formed in the last 1Gyr of the SMC history in a roughly continuous way with periods ofenhancements. The two super-shells 37A and 304A detected in the HIdistribution are clearly visible in the age distribution of theclusters: an enhancement in the cluster formation rate has taken placefrom the epoch of the shell formation. A tight correlation between youngclusters and the HI intensity is found. The degree of correlation isdecreasing with the age of the clusters. Clusters older than 300 Myr arelocated away from the HI peaks. Clusters and associations younger than10 Myr are related to the CO clouds in the SW region of the SMC disk. Apositive correlation between the location of the young clusters and thevelocity dispersion field of the atomic gas is derived only for theshell 304A, suggesting that the cloud-cloud collision is probably notthe most important mechanism of cluster formation. Evidence ofgravitational triggered episode due to the most recent close interactionbetween SMC and LMC is found both in the cluster andfield star distribution.
| Evolutionary population synthesis: models, analysis of the ingredients and application to high-z galaxies Evolutionary population synthesis models for a wide range ofmetallicities, ages, star formation histories, initial mass functionsand horizontal branch morphologies, including blue morphologies at highmetallicity, are computed. The model output comprises spectral energydistributions, colours, stellar M/L ratios, bolometric corrections andnear-infrared (IR) spectral line indices. The energetics of the postmain sequence evolutionary phases are evaluated with the fuelconsumption theorem. The impact on the models of the stellarevolutionary tracks (in particular with and without overshooting) isassessed. We find modest differences in synthetic broad-band colours asinduced by the use of different tracks in our code [e.g. Δ(V-K) ~0.08 mag, Δ(B-V) ~ 0.03 mag]. Noticeably, these differences aresubstantially smaller than the scatter among other models in theliterature, even when the latter adopt the same evolutionary tracks. Themodels are calibrated with globular cluster data from the Milky Way forold ages, and the Magellanic clouds plus the merger remnant galaxy NGC7252, both for young ages of ~0.1-2Gyr, in a large wavelength range fromthe U band to the K band. Particular emphasis is put on the contributionfrom the thermally pulsing asymptotic giant branch (TP-AGB) phase. Weshow that this evolutionary phase is crucial for the modelling of youngstellar populations by direct comparison with observed spectral energydistributions of Magellanic cloud clusters, which are characterized byrelatively high fluxes, both blueward and redward of the V band. We findthat the combination of the near-IR spectral indices C2 andH2O can be used to determine the metallicity of ~1 Gyrstellar populations. As an illustrative application, we re-analyse thespectral energy distributions of some of the high-z galaxies (2.4<~z<~ 2.9) observed with the Spitzer Space Telescope by Yan et al.Their high rest-frame near-IR fluxes is reproduced very well with themodels including TP-AGB stars for ages in the range ~0.6-1.5Gyr,suggesting formation redshifts for these objects around z~ 3-6.
| The Star Clusters of the Small Magellanic Cloud: Age Distribution We present age measurements for 195 star clusters in the SmallMagellanic Cloud based on comparison of integrated colors measured fromthe Magellanic Clouds Photometric Survey with models of simple stellarpopulations. We find that the modeled nonuniform changes of clustercolors with age can lead to spurious age peaks in the cluster agedistribution; that the observed numbers of clusters with age t declinessmoothly as t-2.1 that for an assumed initial cluster massfunction scaling as M-2, the dependence of the clusterdisruption time on mass is proportional to M0.48; thatdespite the apparent abundance of young clusters, the dominant epoch ofcluster formation was the initial one; and that there are significantdifferences in the spatial distribution of clusters of different ages.Because of limited precision in our age measurements, we cannot addressthe question of detailed correspondence between the cluster age functionand the field star formation history. However, this sample provides aninitial guide as to which clusters to target in more detailed studies ofspecific age intervals.
| Infrared Surface Brightness Fluctuations of Magellanic Star Clusters We present surface brightness fluctuations (SBFs) in the near-IR for 191Magellanic star clusters available in the Second Incremental and All SkyData releases of the Two Micron All Sky Survey (2MASS) and compare themwith SBFs of Fornax Cluster galaxies and with predictions from stellarpopulation models as well. We also construct color-magnitude diagrams(CMDs) for these clusters using the 2MASS Point Source Catalog (PSC).Our goals are twofold. The first is to provide an empirical calibrationof near-IR SBFs, given that existing stellar population synthesis modelsare particularly discrepant in the near-IR. Second, whereas mostprevious SBF studies have focused on old, metal-rich populations, thisis the first application to a system with such a wide range of ages(~106 to more than 1010 yr, i.e., 4 orders ofmagnitude), at the same time that the clusters have a very narrow rangeof metallicities (Z~0.0006-0.01, i.e., 1 order of magnitude only). Sincestellar population synthesis models predict a more complex sensitivityof SBFs to metallicity and age in the near-IR than in the optical, thisanalysis offers a unique way of disentangling the effects of age andmetallicity. We find a satisfactory agreement between models and data.We also confirm that near-IR fluctuations and fluctuation colors aremostly driven by age in the Magellanic cluster populations and that inthis respect they constitute a sequence in which the Fornax Clustergalaxies fit adequately. Fluctuations are powered by red supergiantswith high-mass precursors in young populations and by intermediate-massstars populating the asymptotic giant branch in intermediate-agepopulations. For old populations, the trend with age of both fluctuationmagnitudes and colors can be explained straightforwardly by evolution inthe structure and morphology of the red giant branch. Moreover,fluctuation colors display a tendency to redden with age that can befitted by a straight line. For the star clusters only,(H-Ks)=(0.21+/-0.03)log(age)-(1.29+/-0.22) once galaxies areincluded, (H-Ks)=(0.20+/-0.02)log(age)-(1.25+/-0.16).Finally, we use for the first time a Poissonian approach to establishthe error bars of fluctuation measurements, instead of the customaryMonte Carlo simulations.This research has made use of the NASA/ IPAC Infrared Science Archive,which is operated by the Jet Propulsion Laboratory, California Instituteof Technology, under contract with the National Aeronautics and SpaceAdministration.
| Dating star clusters in the Small Magellanic Cloud by means of integrated spectra In this study flux-calibrated integrated spectra in the range(3600-6800) Å are presented for 16 concentrated star clusters inthe Small Magellanic Cloud (SMC), approximately half of which constituteunstudied objects. We have estimated ages and foreground interstellarreddening values from the comparison of the line strengths and continuumdistribution of the cluster spectra with those of template clusterspectra with known parameters. Most of the sample clusters are youngblue clusters (6-50 Myr), while L 28, NGC 643 and L 114 are found to beintermediate-age clusters (1-6 Gyr). One well known SMC cluster (NGC416) was observed for comparison purposes. The sample includes clustersin the surroundings and main body of the SMC, and the derived foregroundreddening values are in the range 0.00 <= E(B-V) <= 0.15. Thepresent data also make up a cluster spectral library at SMC metallicity.Based on observations made at Complejo Astronómico El Leoncito,which is operated under agreement between the Consejo Nacional deInvestigaciones Científicas y Técnicas de laRepública Argentina and the National Universities of La Plata,Córdoba and San Juan, Argentina.
| Updating the Census of Star Clusters in the Small Magellanic Cloud Surveys using CCD detectors are retrieving bright and faint catalogedclusters and revealing new ones in the Magellanic Clouds. This paperdiscusses the contribution of the OGLE Survey to the overall census ofstar clusters in the Small Magellanic Cloud (SMC). A detailedcross-identification indicates that the new objects in the SMC OGLEcatalog are 46. The increase in the number of cataloged clusters is ~7%,the total sample being ~700. This updated census includes embeddedclusters in H II regions and a density range attaining loose systems.
| The Optical Gravitational Lensing Experiment. Cepheids in Star Clusters from the Magellanic Clouds We present Cepheids located in the close neighborhood of star clustersfrom the Magellanic Clouds. 204 and 132 such stars were found in the LMCand SMC, respectively. The lists of objects were constructed based oncatalogs of Cepheids and star clusters, recently published by theOGLE-II collaboration. Location of selected Cepheids on the skyindicates that many of them are very likely cluster members. Photometricdata of Cepheids and clusters are available from the OGLE Internetarchive.
| The Optical Gravitational Lensing Experiment. Age of Star Clusters from the SMC We present determination of age of clusters from 2.4 square degreeregion of the SMC bar. The photometric data were taken from the BVI mapsof the SMC and catalog of clusters in this galaxy obtained during theOGLE-II microlensing survey. For 93 well populated SMC clusters theirage is derived with the standard procedure of isochrone fitting. Thedistribution of age of cluster from the SMC is presented. It indicateseither non-uniform process of cluster formation or very effectivedisruption of clusters.
| The Optical Gravitational Lensing Experiment. Variable Stars in Star Clusters of the Magellanic Clouds. I.Eclipsing Systems in the Clusters of the SMC The list of 127 eclipsing stars in optical coincidence with starclusters from the SMC is presented. It was prepared using the catalogsof eclipsing systems and star clusters from the SMC based onobservations collected during the OGLE-II microlensing project. Locationof 12 eclipsing stars in the color-magnitude diagram of clusters allowsto exclude their membership. Photometric data of 73 systems supporttheir membership. The remaining 42 objects were found in loose, faintclusters and therefore no conclusive statement about their membershipcan be made. All presented data are available from the OGLE archive.
| A radio continuum study of the Magellanic Clouds. VIII. Discrete sources common to radio and infrared surveys of the Magellanic Clouds We compare Parkes Telescope radio surveys with the IRAS Infrared (IR)surveys of the Magellanic Clouds (MCs). We find 130 discrete sources incommon towards the Large Magellanic Cloud (LMC) with both radio and IRemission. These 130 sources are mainly H Ii regions (89) and supernovaremnants (21). For 12 of the sources we have no identification and eightare background objects. We find 38 sources in common for the SmallMagellanic Cloud (SMC). Most of these sources are intrinsic (31) to theSMC, five sources are previously known background galaxies and twosources remain ambiguous. A flux density comparison of the radio and IRsources shows very good correlation and we note that the strongestsources at both radio and IR frequencies are H Ii regions. From theradio-IR comparison we propose that some 40 new sources in the LMC and10 in the SMC are H Ii regions or SNRs. All these new sources are alsoidentified in optical surveys.
| A radio continuum study of the Magellanic Clouds. VII. Discrete radio sources in the Magellanic Clouds We present a study of discrete radio sources in the Magellanic Clouds(MCs) using the latest large-scale radio surveys made with the Parkesradio telescope between 1.4 and 8.55 GHz. These surveys achieved highersensitivity then previous surveys done with the Parkes telescope and sothe number of discrete radio sources detected towards the MCs hasincreased by factor of five. Also, we have obtained improved positions,flux densities and radio spectral indices for all of these sources. Atotal of 483 sources towards the Large Magellanic Cloud (LMC) and 224towards the Small Magellanic Cloud (SMC) have been detected at at leastone radio frequency. Most of the MC's sources have been classified inone of three groups: SNRs, H Ii regions or background sources accordingto classification criteria established here. In total, 209 discreteradio sources in the LMC and the 37 sources in the SMC are classifiedhere to be either H Ii regions or SNRs. We investigate their luminosityfunctions as well as the statistics of background sources behind theMCs. Also, we examine the distribution of SNRs and H Ii regions in theMCs. Tables 5 and 6 are only available electronically at the CDS via ftp130.79.128.5 or via http://cdsweb.u-strasbg.fr/Abstract.html
| Optical Gravitational Lensing Experiment. The Catalog of Clusters in the Small Magellanic Cloud We present the catalog of clusters found in the area of approx 2.4square degree in the central regions of the Small Magellanic Cloud. Thecatalog contains data for 238 clusters, 72 of them are new objects. Foreach cluster equatorial coordinates, radii, approximate number ofmembers, cross-identification, finding chart and color magnitudediagrams: V-(B-V) and V-(V-I) are provided. Photometric data for allclusters presented in the catalog are available from the OGLE Internetarchive.
| Cepheids in MC Clusters: New Observations Not Available
| A radio continuum study of the Magellanic Clouds V. Catalogues of radio sources in the Small Magellanic Cloud at 1.42, 2.45, 4.75, 4.85 and 8.55 GHz We present catalogues of radio sources in the Small Magellanic Cloudfrom observations with the Parkes radio telescope at 1.42, 2.45, 4.75and 8.55 GHz, and an additional catalogue from the Parkes-MIT-NRAOsurvey at 4.85 GHz. A total of 224 sources were detected at at least oneof these frequencies, 60 of which are reported here for the first timeas radio sources. We compare positions and flux densities of thesesources with previously published results and find no significantpositional displacement or flux discrepancies. Tables 2-7 are onlyavailable electronically at the CDS via ftp 130.79.128.5 or athttp://cdsweb.u-strasbg.fr/Abstract.html
| A Revised and Extended Catalog of Magellanic System Clusters, Associations, and Emission Nebulae. I. Small Magellanic Cloud and Bridge A survey of extended objects in the Magellanic System was carried out onthe ESO/SERC R and J Sky Survey Atlases. The present work is dedicatedto the Small Magellanic Cloud and to the inter-Magellanic Cloud region("Bridge") totaling 1188 objects, of which 554 are classified as starclusters, 343 are emissionless associations, and 291 are related toemission nebulae. The survey includes cross-identifications amongcatalogs, and we present 284 new objects. We provide accurate positions,classification, homogeneous sizes, and position angles, as well asinformation on cluster pairs and hierarchical relation for superimposedobjects. Two clumps of extended objects in the Bridge and one at theSmall Magellanic Cloud wing tip might be currently forming dwarfspheroidal galaxies.
| A New Catalogue of Hα Emission Line Stars and Small Nebulae in the Small Magellanic Cloud An objective-prism survey of the Small Magellanic Cloud has beenperformed through an Hα + [N II] interference filter, using the0.90 m Curtis Schmidt telescope of Cerro Tololo. 1898 emission-lineobjects have been detected in the main body of this galaxy, almostquadrupling the number of those found, in the same region, by theprevious objective-prism surveys. Among these objects are newlydiscovered planetary nebulae, compact HII regions and late-type stars.Continuum intensity, as well as the shape and relative strength of theHα emission-line have been estimated; coordinates, cross-identifications for the listed objects and 2.25 arcmin square findingcharts for all the objects are provided.
| Chemically distinct galactic nuclei Observations with the MPFS panoramic spectrophotometer at the 6-mtelescope are reported for 12 galaxies of various morphological types.Radial variations of the equivalent width of the absorption lines MgI5175 and FeI 5270, 5335 up to radii of 6-10 arcsec are obtained. Anuneven increase in metallicity of 4-20 times between the nucleus and itssurrounding bulge is found in seven galaxies. It is shown that the jumpis related to the dynamical distinction of a galactic nucleus, i.e., itsrapid solid-body rotation.
| Accurate positions for SMC clusters Positions of 203 SMC clusters accurate to + or - 5 arcsec are reported.The astrometry method used is briefly described. Plans for futureMagellanic Cloud cluster astrometry are summarized.
| The asymptotic giant branch of Magellanic Cloud clusters The present search for carbon and M-type asymptotic giant branch (AGB)stars in the 39 clusters of the Magellanic Clouds has yieldedidentifications and near-IR photometry for about 400 such stars. TheSearle et al. (1980) cluster-age-related classification scheme is abasic element of the present analysis of these data. In a C-M diagram,the cluster M stars shift steadily redward as one proceeds from clustersof SWB type I to VI, due to the increasing age of the clusters along thesequence. Luminous carbon stars are present only in SWB IV-VI clusters,and are easily distinguished from M stars by their color and luminosity.
| Infrared observations of the Magellanic Clouds. I - The Small Magellanic Cloud Results of IRAS pointed observations in four infrared wavelength bands(12, 25, 60, and 100 microns) for the SMC are presented. Maps withorthogonal scan directions are shown, and a source list containing 219infrared sources is extracted from the data. Comparison with the IRASPoint Source Catalog (PSC) shows that only three entries in this catalogare spurious. All 13 entries in the IRAS Small Scale Structure Catalog(SSS) in the SMC are confirmed. Seventy-two new infrared sources, notincluded in either the PSC or in the SSS are found. The present SMCinfrared source list is compared to other object lists. Two blueglobular clusters, 28 SAO stars, and seven planetary nebulae areidentified. No SMC stars are found. In general there is a goodcorrelation of infrared emission with the distributiion of H II regionsand dark clouds.
| Observed radii and structural parameters of star clusters in the SMC. III The tidal radii, concentration parameters, and masses of 24 starclusters in the SMC have been derived by means of star counts. In thisinvestigation the seven most distant clusters (with projected distancesfrom the rotation center similar to the halo radius) are included aswell, and their masses are found to be about one hundred times lowerthan those of the halo clusters of the Galaxy.
| Age calibration and age distribution for rich star clusters in the Large Magellanic Cloud An empirical relation is presented for estimating the ages of rich starclusters in the Large Magellanic Cloud (LMC), to within a factor ofabout 2, from their integrated UBV colors. The calibration is based onpublished ages for 58 LMC clusters derived from main-sequencephotometry, integrated spectra, or the extent of the asymptotic giantbranches. Using stellar population models, a sample of LMC clusters moremassive than about 10,000 solar masses is isolated, which is correctedfor incompleteness as a function of magnitude. An unbiased agedistribution for three clusters is then determined. The number ofclusters decreases with increasing age in a manner that is qualitativelysimilar to the age distribution for the open clusters in our Galaxy. TheLMC age distribution is, however, flatter, and the median age of theclusters is greater. If the formation rate has been approximatelyconstant over the history of the two galaxies, then the age distributionobtained here implies that clusters are disrupted more slowly in theLMC. The results contain no evidence for bursts in the formation ofclusters, although fluctuations on small time scales and slow variationsover the lifetime of the LMC cannot be ruled out.
| Integrated magnitudes and colors of clusters in the magellanic clouds and Fornax system Data from PV, six-color, and four-color photometric observations ofclusters (38 in the Small Magellanic Cloud, 16 in the Large MagellanicCloud, four in the Fornax system, and NGC 1841) are reported. Theobservations were made in 1951, 1960-1961, 1959-1966, and 1974-1975using various telescopes and photometer setups at Mount StromloObservatory in Australia. Tables of integrated magnitudes and colors(both as originally observed and as reduced to the BV system) arepresented, and comparable published data are shown. The combined V dataare fitted to the theoretical luminosity profiles of King (1966) toestimate the total magnitudes and surface brightness distributions of 33of the clusters. Several sample profile fits are shown. A color-colorplot (V-B vs. G-R) is discussed in terms of identification of clustertypes by color: it is found that globular clusters can be separated fromother types, if all have the same amount of reddening.
| Photometric studies of composite stellar systems. V - Infrared photometry of star clusters in the Magellanic clouds Abstract image available at:http://adsabs.harvard.edu/abs/1983ApJ...266..105P
| The extended giant branches of intermediate age globular clusters in the Magellanic Clouds. II In order to obtain a complete sample of upper asymptotic giant branch(AGB) stars in the red globular clusters of the Magellanic Clouds, aphotographic near-infrared survey of the clusters was conducted. Theresults are compared with previous photometry and the problem of errorarising from variability of carbon stars is addressed. Stars withoutspectra are tentatively classified based on their JHK colors. Apparentand absolute bolometric magnitudes and effective temperatures werecalculated from the IR colors, allowing for the location of the redstars and of the cluster giant branches in the physical H-R diagram tobe determined. Stellar evolution on the AGB is discussed, leading toimproved estimates of the extent of the upper AGB. A carbon star censusis presented and the ages of the clusters is derived with suitablycomplete photometry. On this basis, the chemical enrichment history ofthe Clouds is discussed.
| Redshifts for galaxies in three Yerkes poor clusters Redshifts have been obtained for 11 galaxies in the Yerkes poor clusterAWM 7, five galaxies in AWM 5, and two galaxies in AWM 1. In contrast tothe result for AWM 4 previously noted by Stauffer and Spinrad, both AWM5 and AWM 7 are real clusters with apparent line-of-sight velocitydispersions of 400 km/s and 600 km/s respectively. Surface photometry ofthe cD galaxy in AWM 7, obtained with the Berkeley PDS from a Crossleyplate of the cluster, indicates that it is quite luminous, with anabsolute magnitude to r about 30 kpc of M(v) about -23.5. A roughdynamical estimate of the AWM 7 cD mass from the spectroscopic datagives M(cD) about 2.0 x 10 to the 13th solar masses.
| UBV photometry for star clusters in the Small Magellanic Cloud. Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978A&AS...34..431A&db_key=AST
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